The World's Rarest Gemstone

Some minerals are so rare that only a handful of specimens are known to exist worldwide. A few of these very rare minerals, such as painite, have even been found only in gem-quality specimens. Up until 2005, there were only 25 known specimens of painite in the world, and only a few of them were ever faceted. Other rare gems include jeremejevite, taaffeite, poudretteite and serendibite; all of which are some of the rarest in the world with regard to occurrence. Even well-known gemstones like tanzanite, jadeite and alexandrite are considered by most to be in the top rare gems list. But in the international gem trade, the rarest gemstones are not those with the least occurrence known to man, but instead, the rarest stone titles are awarded to those that draw the highest price per carat at auctions such as Sotheby's and Christie's.

Red Diamond

Based on this criterion, certain colored diamonds are the rarest gemstones in the world, particularly vividly colored natural diamonds that are pink, blue, yellow or green. Among the colored diamond gemstone family, the rarest color variety of of all is the red diamond. In fact, there are only perhaps 20 to 30 red diamonds known to exist, and most weigh less than half a carat.

In 1980, the highest auction price paid for a diamond was $127,000 per carat for a 7.27-carat pink diamond. That record was shattered in 1987 by the first high-quality red diamond to be sold at auction; the 0.95-carat Hancock Red. It sold for over $926,000 per carat! The Hancock Red was sold by the heirs of the American owner, Warren Hancock, a Montana rancher and diamond collector. Mr. Hancock bought all of his diamonds at retail prices from his local jeweler, and he had reportedly paid $13,500 for the 0.95-carat red diamond in 1956. It is fair to say this was one of the greatest gemstone investments of the century.

A new price record was set in November 2007 at Christie's in Geneva. A ring containing a rare 2.26-carat purplish-red diamond sold for $2.6 million; about $1.15 million per carat. Later in 2015, a 12.08-carat vivid blue diamond claimed the newest world record, fetching $4 million USD per carat. The $4 million USD price tag beat the previous record by over $1 million USD. But the most recent record-breaker for most expensive jewel goes to the 14.62-carat Oppenheimer Blue Diamond, which sold at Christie's in Geneva for a whopping $57.5 million USD.

The largest-known red diamond that has been graded by the Gemological Institute of America (GIA) is the 5.11-carat Moussaieff Red Diamond. It is a trillion-cut diamond rated as Fancy Red by the GIA. This diamond was reportedly found by a Brazilian farmer in the mid-1990s as a rough stone of about 11 carats. The diamond was purchased and cut by the William Goldberg Diamond Corp., where it went by its original name, the Red Shield. It is currently owned by Moussaieff Jewellers Ltd., the purchase price was rumored to be approximately $8 million.

Some colored diamonds, such as blue and yellow diamonds, are colored by trace amounts of impurities. Yellow and champagne diamonds are colored by nitrogen, and blue diamonds by boron. However, red and pink diamonds are not colored by impurities; rather their color is the result of minute defects in the crystal lattice. The highest price paid for an orange diamond, was for a 14.82-carat stone known as 'The Orange', which fetched almost $2.4 million USD per carat.

Other Record-Breaking Rare Gemstone Types

Other notable record-breaking rare gems include more red gemstones, including a 15.04-carat Burmese ruby, known as the 'Crimson Flame'. In 2015, a private buyer in Hong Kong paid $18 million USD for the remarkable ruby.

Very few gemstone types other than diamond have ever been known to fetch more than $100,000 USD per carat; interestingly, among these rare gems is another ruby, known as 'The Sunrise Ruby'. The Sunrise Ruby weighs 25.59 carats and fetched almost $1.2 million USD per carat at auction. Pink gemstones set new records too. One vivid pink diamond of 16.08 carats was sold for $28.5 million USD. Surprisingly, it was acquired by the same buyer as the 12.03-carat 'Blue Moon of Josephine' diamond. The Unique Pink, a 15.38-carat pink diamond, also made new records when it sold for $31.6 million USD. The most expensive blue gemstones sold include several sapphires on record, including the 392.52-carat Blue Belle of Asia, which sold for approximately $44,060 per carat; the 27.68-carat Jewel of Kashmir, which sold for for over $242,000 USD per carat; and the 'Unnamed'; a 35.08-carat beauty that fetched roughly $211,000 per carat.